ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 3, pp. 470–471. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.A. Shklyarenko, A.V. Moskvin, E.V. Fedorova, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 3,
pp. 469–470.
SHORT
COMMUNICATIONS
Oxidation of 4-Amino-5-aryl-4H-1,2,4-triazole-3-thiols
A. A. Shklyarenko, A. V. Moskvin, and E. V. Fedorova
St. Petersburg State Chemical and Pharmaceutical Academy, ul. prof. Popova 14, St. Petersburg, 197376 Russia
e-mail: tjema@yandex.ru
Received May 5, 2010
DOI: 10.1134/S1070428011030298
Heterocyclic thiols of the 1,2,4-triazole series, in
particular 4-amino-5-aryl-4H-1,2,4-triazole-3-thiols I
exhibit a broad spectrum of biological activity, such as
antibacterial, antifungal, etc. [1–4]. Transformation of
thiols into the corresponding sulfones and sulfonic
acids usually enhances their biological activity [5].
Triazoles I are widely used as starting compounds for
the synthesis of fused heterocycles [6, 7]. On the other
hand, published data on the oxidation of triazoles I to
sulfonic acids are very few in number, and the reported
oxidation procedures are characterized by low effi-
ciency. The corresponding oxidation products are
formed in ~30% yield [8].
General procedure for the oxidation of 4-amino-
5-aryl-4H-1,2,4-triazole-3-thiols Ia–Id. A mixture of
0.5 g of 4-amino-5-aryl-4H-1,2,4-triazole-3-thiol Ia–
Id and 5 ml of glacial acetic acid was cooled to room
temperature, 1.5 ml of 30% hydrogen peroxide was
added, and the mixture was kept for 1 h on a cold
water bath. The bath was removed, the mixture was
left to stand for a week, and the precipitate was filtered
off and dried.
4-Amino-5-(3-methoxyphenyl)-4H-1,2,4-triazole-
3-sulfonic acid (IIa). Yield 80%, mp 120–121°C. IR
1
spectrum, ν, cm–1: 1220, 1030 (SO2). H NMR spec-
trum, δ, ppm: 3.84 s (3H, OCH3), 7.16–7.18 d (1H,
Harom), 7.46–7.51 t (1H, Harom), 7.62–7.64 s (2H, Harom),
8.0 br.s (2H, NH2), 9.29 s (1H, SO3H). 13C NMR spec-
trum, δC, ppm: 55.5, 114.3, 117.5, 121.2, 123.9, 130.0,
145.9, 151.4, 159.3. Found, %: C 39.95, 38.99; H 3.85,
3.78; N 19.95, 19.84; S 10.73, 11.96. C9H10N4O4S.
Calculated, %: C 40.00; H 3.73; N 20.73; S 11.86.
4-Amino-5-(2-chlorophenyl)-4H-1,2,4-triazole-3-
sulfonic acid (IIb). Yield 65%, mp 104–105°C
(decomp.). IR spectrum, ν, cm–1: 1180, 1100 (SO2).
1H NMR spectrum, δ, ppm: 6.60 br.s (2H, NH2), 7.43–
7.47 t (1H, Harom), 7.50–7.63 m (3H, Harom), 9.67 s (1H,
SO3H). 13C NMR spectrum, δC, ppm: 122.2, 127.4,
129.9, 133.1, 133.4, 145.2. Found, %: C 33.98, 34.00;
H 3.11, 2.48; N 19.84, 19.94; S 11.73, 11.56.
C8H7ClN4O3S. Calculated, %: C 34.98; H 2.57;
N 20.40; S 11.67.
We propose a simple and efficient procedure for
the preparation of triazolesulfonic acids. Oxidation of
4-amino-5-aryl-4H-1,2,4-triazole-3-thiols with 30%
hydrogen peroxide in acetic acid at room temperature
afforded 65–80% of the corresponding sulfonic acids
1
II. The product structure was confirmed by the H and
13C NMR and IR spectra and elemental analyses.
NH2
N
NH2
N
H2O2, AcOH
Ar
SH
Ar
SO2OH
N
N
N
N
Ia–Id
IIa–IId
Ar = 3-MeOC6H4 (a), 2-ClC6H4 (b), 3-FC6H4 (c), 4-BrC6H4 (d).
1
Unlike initial thiols Ia–Id, the H NMR spectra of
sulfonic acids IIIa–IIId lack signal at δ 14–16 ppm
typical of SH proton but contain a signal at δ 9–
10 ppm due to proton of the SO3H group. In addition,
the NH2 signal becomes broadened and shifts toward
weaker field (δ 6.0–8.5 ppm). In the IR spectra of
IIIa–IIId, absorption bands corresponding to stretch-
ing vibrations of the SO2 fragment are observed at
1000–1300 cm–1.
4-Amino-5-(3-fluorophenyl)-4H-1,2,4-triazole-3-
sulfonic acid (IIc). Yield 78%, mp 159–160°C
(decomp.). IR spectrum, ν, cm–1: 1200, 1090 (SO2).
1H NMR spectrum, δ, ppm: 6.10 br.s (2H, NH2), 7.39–
7.42 t (1H, Harom), 7.59–7.64 q (1H, Harom), 7.90–
7.94 d.d (2H, Harom), 9.29 s (1H, SO3H). 13C NMR
spectrum, δC, ppm: 115.4, 118.4, 124.9, 125.9, 130.9,
146.1, 150.8. Found, %: C 36.95, 37.15; H 2.87, 2.56;
470
Shklyarenko
